RESUMEN
A novel selenium dioxide promoted selenylation/cyclization of leucosceptrane sesterterpenoids was reported. Two types of leucosceptrane derivatives with different valence states of selenium atoms (Se2+ and Se4+) were obtained. The mechanisms of these two processes were proposed, and the selenium-containing derivates may serve as intermediates of Riley oxidation that could be trapped with appropriate substrates. Immunosuppressive activity screening revealed that 10 and 11 had obvious inhibitory effects on IFN-γ production, with IC50 values of 5.29 and 17.60 µM, respectively, which were more active than their precursor leucosceptroid A.
Asunto(s)
Óxidos de Selenio , Sesterterpenos , Ciclización , Óxidos de Selenio/química , Sesterterpenos/química , Sesterterpenos/farmacología , Interferón gamma/metabolismo , Inmunosupresores/química , Inmunosupresores/farmacología , Estructura Molecular , Animales , Ratones , Selenio/química , Selenio/farmacologíaRESUMEN
Scoparodane C (1), a diterpenoid with a rare 3,4-seco-3-nor-2,11-epoxy-ent-clerodane scaffold, was obtained from the aerial parts of Isodon scoparius, along with isocopariusines A-E (2-6), five ent-clerodanoids featuring a 5/6-fused ring system, and isocopariusines F-H (7-9), three common ent-clerodanoids. The structures of these previously undescribed compounds were established by a combination of spectroscopic analysis, X-ray diffraction, chemical derivatization, and quantum chemical calculation. Remarkably, isocopariusine B (3) showed strong resistance reversal activity against fluconazole-resistant Candida albicans.
Asunto(s)
Candida albicans , Isodon , Componentes Aéreos de las Plantas , Componentes Aéreos de las Plantas/química , Isodon/química , Estructura Molecular , Candida albicans/efectos de los fármacos , Pruebas de Sensibilidad Microbiana , Antifúngicos/farmacología , Antifúngicos/química , Antifúngicos/aislamiento & purificación , Diterpenos de Tipo Clerodano/química , Diterpenos de Tipo Clerodano/farmacología , Diterpenos de Tipo Clerodano/aislamiento & purificación , Modelos MolecularesRESUMEN
Three new ent-kaurane diterpenoids, silvaticusins A-C (1-3), along with a new ent-kaurane dimer silvaticusin D (4) were isolated from the aerial parts of Isodon silvaticus. The structures of these new compounds were established mainly by comprehensive analysis of their NMR and MS data. The absolute configuration of compounds 1 and 4 were determined using a single-crystal X-ray diffraction and computational methods, respectively. Compounds 2 and 3 were found to exhibit remarkable cytotoxic effects against five human tumor cell lines (HL-60, A-549, SMMC-7721, MDA-MB-231, and SW-480), with IC50 values spanning from 1.27 ± 0.08 to 7.52 ± 0.33 µM.
RESUMEN
Twelve previously undescribed ophiobolin-type sesterterpenoids, undobolins A-L (1-12), were isolated from Aspergillus undulatus, and their structures were elucidated by spectroscopic analysis, ECD calculations, and single-crystal X-ray diffraction experiments. Compound 1 was the second example of 20-nor-ophiobolin reported, while compounds 2-6 were notable for oxygenation of C-2, and compound 6 showed significant inhibitory activity against ConA-induced T lymphocyte proliferation with an IC50 value of 2.3 µM, which suggests a promising new direction in the quest for immunosuppressive agents.
Asunto(s)
Aspergillus , Sesterterpenos , Sesterterpenos/farmacología , Sesterterpenos/química , Sesterterpenos/aislamiento & purificación , Aspergillus/química , Estructura Molecular , Animales , Linfocitos T/efectos de los fármacos , Cristalografía por Rayos X , Inmunosupresores/farmacología , Inmunosupresores/química , Inmunosupresores/aislamiento & purificación , Ratones , Proliferación Celular/efectos de los fármacosRESUMEN
Isoxerophilusins A (1) and B (2), two unprecedented diterpene heterodimers biogenetically from ent-atisanes and abietanes, were isolated from the rhizomes of Isodon xerophilus. Their structures were determined by extensive spectroscopic analysis and single-crystal X-ray diffraction. Selective esterification of 1 generated 11 new derivatives. All derivatives showed excellent α-glucosidase inhibitory activity in comparison to acarbose. Compounds 12 and 13 demonstrated significant inhibition against α-glucosidase with IC50 values of 4.92 and 3.83 µM, respectively.
Asunto(s)
Diterpenos , Inhibidores de Glicósido Hidrolasas , Isodon , alfa-Glucosidasas , Inhibidores de Glicósido Hidrolasas/química , Inhibidores de Glicósido Hidrolasas/farmacología , Inhibidores de Glicósido Hidrolasas/aislamiento & purificación , Diterpenos/química , Diterpenos/farmacología , Diterpenos/aislamiento & purificación , alfa-Glucosidasas/metabolismo , Estructura Molecular , Isodon/química , Dimerización , Cristalografía por Rayos X , Relación Estructura-Actividad , Rizoma/químicaRESUMEN
Five undescribed leucosesterterpane sesterterpenoids, leucosceptrines A-E, two undescribed penta-nor-leucosesterterpane (C20) sesterterpenoids, nor-leucosceptrines A and B, and three known analogues, were obtained from the aerial parts of Leucosceptrum canum of Chinese origin. Leucosceptrines A-C are the first examples of leucosesterterpane-type sesterterpenoids with unclosed dihydropyran rings and reverse configurations at chiral centers C-4 and/or C-12. Nor-leucosceptrines A and B possesses an unusual penta-nor-leucosesterterpane skeleton. Their structures were unambiguously elucidated through comprehensive spectroscopic analyses and single-crystal X-ray diffraction. A plausible biogenetic pathway for these sesterterpenoids was proposed. The immunosuppressive effects of these isolates on the secretion of the cytokine IFN-γ by T cells stimulated with anti-CD3/CD28 monoclonal antibodies were observed with different potencies.
Asunto(s)
Inmunosupresores , Sesterterpenos , Sesterterpenos/química , Sesterterpenos/farmacología , Sesterterpenos/aislamiento & purificación , Inmunosupresores/farmacología , Inmunosupresores/química , Inmunosupresores/aislamiento & purificación , Estructura Molecular , Humanos , Linfocitos T/efectos de los fármacos , Relación Estructura-Actividad , Conformación Molecular , Interferón gammaRESUMEN
Nickel is the most widely used inexpensive active metal center of the heterogeneous catalysts for CO2 hydrogenation to methane. However, Ni-based catalysts suffer from severe deactivation in CO2 methanation reaction due to the irreversible sintering and coke deposition caused by the inevitable localized hotspots generated during the vigorously exothermic reaction. Herein, we demonstrate the inverse CeAlOx/Ni composite constructed on the Ni-foam structure support realizes remarkable CO2 methanation catalytic activity and stability in a wide operation temperature range from 240 to 600 °C. Significantly, CeAlOx/Ni/Ni-foam catalyst maintains its initial activity after seven drastic heating-cooling cycles from RT to 240 to 600 °C. Meanwhile, the structure catalyst also shows water resistance and long-term stability under reaction condition. The promising thermal stability and water-resistance of CeAlOx/Ni/Ni-foam originate from the excellent heat and mass transport efficiency which eliminates local hotspots and the formation of Ni-foam stabilized CeAlOx/Ni inverse composites which effectively anchored the active species and prevents carbon deposition from CH4 decomposition.
RESUMEN
Natural products and their analogues are significant sources of therapeutic lead compounds. However, synthetic strategies for generating large collections of these molecules remain a significant challenge. The most difficult step in their synthesis is the design of a common intermediate that can be easily transformed into natural products belonging to different families. This study demonstrates the evolution of synthetic tactics designed to assemble the functionalized piperidines present in indole alkaloids from a common intermediate. More importantly, we also report a previously unknown Ir- and Er-catalyzed dehydrogenative spirocyclization reaction that enables direct access to spirocyclic oxindole alkaloids. As a practical application, the asymmetric total syntheses of 29 natural alkaloids belonging to different families were accomplished by following a uniform synthetic route. The proposed methodology extends the capability of the iridium-catalyzed dehydrogenative coupling reaction to the realm of indole-alkaloid synthesis and provides new opportunities for the efficient preparation of natural product-like molecules.
Asunto(s)
Alcaloides , Productos Biológicos , Humanos , Estereoisomerismo , Alcaloides Indólicos , OxindolesRESUMEN
[4 + 2] cycloaddition has led to diverse polycyclic chiral architectures, serving as novel sources for organic synthesis and biological exploration. Here, an unprecedented class of cadinane sesquiterpene [4 + 2] dimers, henryinins A-E (1-5), with a unique 6/6/6/6/6-fused pentacyclic system, were isolated from Schisandra henryi. The divergent total syntheses of compounds 1-5 and their enantiomers (6-10) were concisely accomplished in eight linear steps using a protection-free approach. Mechanistic studies illustrated the origin of selectivity in the key [4 + 2] cycloaddition as well as the inhibition of reaction pathway bifurcation via desymmetrization. The chemical proteomics results showed that a pair of enantiomers shared common targets (PRDX5 C100 and BLMH C73) and had unique targets (USP45 C588 for 4 and COG7 C419 for 9). This work provides experimental evidence for the discovery of unprecedented cadinane dimers from selective Diels-Alder reaction and a powerful strategy to explore the biological properties of natural products.
RESUMEN
Exploitation of key protected wild plant resources makes great sense, but their limited populations become the major barrier. A particular strategy for breaking this barrier was inspired by the exploration of a resource-saving fungal endophyte Penicillium sp. DG23, which inhabits the key protected wild plant Schisandra macrocarpa. Chemical studies on the cultures of this strain afforded eight novel indole diterpenoids, schipenindolenes A-H (1-8), belonging to six diverse skeleton types. Importantly, semisyntheses suggested some key nonenzymatic reactions constructing these molecules and provided targeted compounds, in particular schipenindolene A (Spidâ A, 1) with low natural abundance. Remarkably, Spidâ A was the most potent HMG-CoA reductase (HMGCR) degrader among the indole diterpenoid family. It degraded statin-induced accumulation of HMGCR protein, decreased cholesterol levels and acted synergistically with statin to further lower cholesterol. Mechanistically, transcriptomic and proteomic profiling suggested that Spidâ A potentially activated the endoplasmic reticulum-associated degradation (ERAD) pathway to enhance the degradation of HMGCR, while simultaneously inhibiting the statin-activated expression of many key enzymes in the cholesterol and fatty acid synthesis pathways, thereby strengthening the efficacy of statins and potentially reducing the side effects of statins. Collectively, this study suggests the potential of Spidâ A for treating cardiovascular disease.
Asunto(s)
Acilcoenzima A , Inhibidores de Hidroximetilglutaril-CoA Reductasas , Inhibidores de Hidroximetilglutaril-CoA Reductasas/farmacología , Inhibidores de Hidroximetilglutaril-CoA Reductasas/uso terapéutico , Degradación Asociada con el Retículo Endoplásmico , Proteómica , Colesterol/metabolismo , IndolesRESUMEN
Spirophyllines A-D (1-4), four new spirooxindole alkaloids all characterized by the spiro[pyrrolidin-3,3'-oxindole] core and a rare isoxazolidine ring, were isolated from Uncaria rhynchophylla. Their structures were determined by spectroscopic methods and confirmed by X-ray crystallography. Based on the biomimetic semisynthesis strategy, compounds 1-8 were synthesized in three steps via the key reactions of 1,3-dipolar cycloaddition and Krapcho decarboxylation from corynoxeine. Interestingly, compound 3 showed moderate inhibitory activity against the Kv1.5 potassium channel (IC50 = 9.1 µM).
Asunto(s)
Alcaloides , Uncaria , Alcaloides/química , Biomimética , Análisis Espectral , Uncaria/químicaRESUMEN
Five new cyclopiazonic acid related indole alkaloids, pegriseofamines A-E (1-5), were isolated from the fungus Penicillium griseofulvum. Their structures and absolute configurations were determined by NMR, HRESIMS, quantum-chemical calculation, and X-ray diffraction experiments. Among them, pegriseofamine A (1) possesses an undescribed 6/5/6/7 tetracyclic ring system generated by the fusion of an azepine and an indole unit via a cyclohexane, and the postulated biosynthetic origin of 1 was discussed. Compound 4 could relieve liver injury and prevent hepatocyte apoptosis in ConA-induced autoimmune liver disease.
Asunto(s)
Alcaloides Indólicos , Penicillium , Alcaloides Indólicos/química , Penicillium/química , Hongos , Estructura MolecularRESUMEN
(+)-Isoscopariusins B (1) and C (2), two meroditerpenoids containing a 6/6/4 tricyclic carbon skeleton and seven continuous stereocenters, were identified from Isodon scoparius. The structures were determined by nuclear magnetic resonance analysis and concise biomimetic syntheses from readily available alkene 5 in seven and six steps, respectively. An intermolecular [2+2] photocycloaddition with cooperative catalysis of a Lewis acid and an Ir photocatalyst was used to construct a cyclobutane core with four stereogenic centers.
Asunto(s)
Ciclobutanos , Isodon , Estructura Molecular , Biomimética , Espectroscopía de Resonancia Magnética , Isodon/química , Catálisis , EstereoisomerismoRESUMEN
Twenty new ent-kaurane diterpenoids, wardiisins A-T (1-20), along with two previously undescribed artefactual compounds (21 and 22) and twelve known analogues (23-34), were isolated from the aerial part of Isodon wardii. Their structures were elucidated by comprehensive analysis of spectroscopic data and single-crystal X-ray diffraction, and most of them were found to bear unusual C-12 oxygenation. Compounds 4, 7, 8, 19, 20, 21 exhibited remarkable cytotoxicity against the cancer cell lines HL-60, SMMC-7721, A-549, MDA-MB-231, and SW480, with IC50 values ranging from 0.3 to 5.2 µM. Moreover, 7 was found to induce G2/M cell cycle arrest and promote apoptosis in SW480 cell lines.
Asunto(s)
Antineoplásicos Fitogénicos , Antineoplásicos , Diterpenos de Tipo Kaurano , Diterpenos , Isodon , Humanos , Diterpenos de Tipo Kaurano/farmacología , Diterpenos de Tipo Kaurano/química , Isodon/química , Antineoplásicos Fitogénicos/farmacología , Antineoplásicos Fitogénicos/química , Ensayos de Selección de Medicamentos Antitumorales , Componentes Aéreos de las Plantas/química , Antineoplásicos/farmacología , Antineoplásicos/análisis , Estructura MolecularRESUMEN
Investigation of the alkaloids from Myrioneuron effusum leads to the isolation of myrionsumamide A (1), a pair of enantiomeric alkaloids with an unprecedented tetracyclic system skeleton. These two alkaloids were separated by chiral HPLC with a ratio of 3 : 5 from the scalemic mixture. Their structures including absolute configurations were determined by NMR spectroscopy, X-ray diffraction data and ECD calculations. Both (+)-1 and (-)-1 showed antibacterial activity against Staphylococcus aureus with MIC at 7.81 µg ml-1.
RESUMEN
Four emestrin hybrid polymers, asperemestrins A-D (1-4, respectively), were isolated from the fungus Aspergillus nidulans. Asperemestrins A-C are the first examples of emestrin-sterigmatocystin heterodimers bearing a 7/5/6/6/5/5/6/6/6 nonacyclic system with a 2,5-diazabicyclo[2.2.2]octane-3,6-dione core, while asperemestrin D features an unprecedented 2,15-dithia-17,19-diazabicyclo[14.2.2]icosa-4,8-diene-12,18,20-trione core skeleton. Their structures were determined by extensive spectroscopic data, electronic circular dichroism calculations, and single-crystal X-ray diffraction. Asperemestrin B showed moderate cytotoxicity against cancer cell lines, including SU-DHL-2, HEPG2, and HL-60.
Asunto(s)
Aspergillus nidulans , Aspergillus nidulans/metabolismo , Dicroismo Circular , Humanos , Estructura Molecular , Octanos , Piperazinas , Polímeros , Esterigmatocistina/metabolismoRESUMEN
Chemical studies on the culture broth of the endophytic fungus Alternaria sp. J030 led to the identification of three benzylated hydroxyacetophenone derivatives, bauvaroalterins A-C (1-3), and 34 structurally diverse metabolites (4-37). The new structures were elucidated by extensive spectroscopic analyses including UV, IR, 1D and 2D NMR, HR-ESI-MS, and further confirmed using single crystal X-ray diffraction. The inâ vitro anti-neuroinflammatory effects of the co-isolated metabolites were evaluated in lipopolysaccharide (LPS)-stimulated microglial cells. Compounds 1-3 were shown to significantly reduce LPS-induced NO production by inhibiting the expression of iNOS, as well as inhibiting LPS-induced production of the inflammatory factors TNF-α, IL-1ß and IL-6. Further studies revealed that 1-3 were capable of down-regulating the expression of NF-κB subunits p50 and p65, thereby suppressing the activation of NF-κB by inhibiting the LPS-induced phosphorylation of IκB-α. Together these findings demonstrate that bauvaroalterins A-C (1-3) exert anti-neuroinflammatory effects via inhibition of the NF-κB/iNOS signalling pathway in LPS induced BV-2 cells.
Asunto(s)
Lipopolisacáridos , FN-kappa B , Lipopolisacáridos/farmacología , Inhibidor NF-kappaB alfa/metabolismo , FN-kappa B/metabolismo , Factor de Necrosis Tumoral alfa/metabolismo , Alternaria/metabolismo , Antiinflamatorios , Interleucina-6/metabolismo , MicroglíaRESUMEN
Four undescribed ergostane-type steroids, (22E,24R)-4α,5α-epoxyergosta-9α,14ß-dihydroxy-7,22-diene-3,6-dione, (22E,24R)-4α,5α-epoxyergosta-9α,14α-dihydroxy-7,22-diene-3,6-dione, 12α-hydroxyergosta-7,22,24(28)-triene-3-one, and 3ß,12α-dihydroxyergosta-7,24(28)-diene, along with a known congener (22E,24R)-9α,14ß-dihydroxyergosta-4,7,22-triene-3,6-dione, were isolated from the fungus Lasiodiplodia pseudotheobromae. Their structures were elucidated using NMR, HRESIMS, ECD calculation, and X-ray diï¬raction analyses. (22E,24R)-4α,5α-epoxyergosta-9α,14ß-dihydroxy-7,22-diene-3,6-dione and (22E,24R)-4α,5α-epoxyergosta-9α,14α-dihydroxy-7,22-diene-3,6-dione are a pair of C-14 epimers possessing an unusual epoxy group between C-4 and C-5, which was demonstrated using single-crystal X-ray diï¬raction analyses. The absolute conï¬gurations of 12α-hydroxyergosta-7,22,24(28)-triene-3-one and 3ß,12α-dihydroxyergosta-7,24(28)-diene were determined by ECD calculations. Moreover, 3ß,12α-dihydroxyergosta-7,24(28)-diene exhibited neuroprotective activity in vitro in glutamate-treated SH-SY5Y cell lines.
Asunto(s)
Ascomicetos , Neuroblastoma , Ergosterol/análogos & derivados , Humanos , Estructura Molecular , Esteroides/químicaRESUMEN
Scopariusicides D-M (1-10), ten new ent-clerodane-based meroditerpenoids with a cyclobutane-fused γ/δ-lactone core, were isolated from Isodon scoparius. Their structures were determined by comprehensive analysis of spectroscopic data, single-crystal X-ray diffraction, chemical transformation, and TDDFT ECD calculation. A plausible biosynthetic pathway of 1-10 was proposed in which the asymmetrical cyclobutane ring was formed via a crossed "head-to-tail" intermolecular [2 + 2] cycloaddition in anti/syn facial approaches between an ent-clerodane lactone and a cis-4-hydroxycinnamic acid. Bioactivity evaluation manifested that 5 exhibited significant neuroprotective effect against corticosterone-induced injury in PC12 cells, while 6 and 7 exhibited moderate immunosuppressive activity against human T cell proliferation stimulated by anti-CD3/anti-CD28 mAb.
Asunto(s)
Antineoplásicos Fitogénicos , Ciclobutanos , Diterpenos de Tipo Clerodano , Isodon , Animales , Antineoplásicos Fitogénicos/farmacología , Ciclobutanos/farmacología , Diterpenos de Tipo Clerodano/farmacología , Ensayos de Selección de Medicamentos Antitumorales , Humanos , Isodon/química , Lactonas/farmacología , Estructura Molecular , RatasRESUMEN
A pair of new tetrahydrofuran lignan enantiomers, (±)-schibiculatin A [(±)-1], a new enedione lignan, schibiculatin B (2), two new cadinane-type sesquiterpenoids, schibiculatins C (3) and D (4), along with two known seco-cadinane-type sesquiterpenoids (5 and 6) and seven known miscellaneous lignans (7-13) were isolated from the stems of Schisandra bicolor var. tuberculate. The structures of 1-4 were elucidated by comprehensive analysis of their spectroscopic data, quantum chemical calculations, as well as single-crystal X-ray diffraction. A few isolated compounds were tested for their protective activities against corticosterone-induced apoptosis in PC12 cells. Among them, compounds 5 and 6 showed moderate activities.